In conventional IC engine spark plugs of the type currently in widespread use, the ground electrode terminates in a single arm or gap-defining end portion which extends radially of the plug's center electrode at a region where it is spaced axially from the end of the center electrode and is intersected by the center electrode's longitudinal axis. Although such spark plugs work satisfactorily, they nevertheless leave considerable room for improvement.
Various spark plug constructions have therefore been proposed in an effort to improve engine and plug performance. For example, the Jay Norris Corporation, on page 5 of the January, 1974 issue of Tennessee Magazine advertised a wideswath, jet-fire fuel ignitor or spark plug in reference to U.S. Pat. No. 2,889,585, claiming that the plug would "walk a strong sure swath of flame from one electrode to another across a semi-conductor bridge to fire each cylinder with absolute reliability."
In another plug construction described in U.S. Pat. No. 2,894,162 which issued to F. Ignatjev, more efficient combustion is asserted by utilizing a special ground electrode construction. According to this patent, the ground electrode is formed with two parallel spaced apart end portions arranged on opposite sides of the center electrode's axis. At their regions remote from their free ends, the parallel end portions extend considerably beyond the peripheral limits of the center electrode and join with a V-shaped portion lying remote from the peripheral limit of the center electrode.
By the foregoing construction, Ignatjev states that the spark will jump between the center electrode and one of the ground electrode's two end portions or tips and furthermore will alternate between the two tips on successive firings.